Astronautical Glossary

Jonathan C. McDowell


In this document I attempt to define the technical terms I use in Jonathan's Space Report and associated material (the General Catalog of Artificial Space Objects, the Deep Space Catalog, etc.).

Some of these definitions reference GCAT (the General Catalog of Artificial Space Objects,

People have strong feelings about the meaning and usage of words, and I am sure some readers will disagree with my choices. Here I am expressing what *I* mean by the words in question, in particular when I use them in these JSR documents. This document is an excuse for me to indulge my tendency for pedantry to a previously unprecedented degree. I have concentrated particulary on including terms which tend to be (in my opinion) misused, or which have multiple senses. I have added extra detail in cases where everyone else is wrong and I'm right (funny how that happens...). You may find the inclusion (or exclusion) of terms to be idiosyncratic. I am happy to consider suggestions for additional terms, but I make no promises.

Words in English often have multiple senses. A word may have a narrow and broad sense (see here `satellite'). Words may be homographs or homonyms, with the same spelling but unrelated meanings (`row', `bat', `down', etc.) I attempt to be explicit about these multiple senses.

I am a dual US-Brit (My parents were UK citizens born in Belfast who moved to England; I was born in Atlanta, Georgia, moved to the UK as a baby, was brought up mainly in England but a bit in the US too, and with one toe in France.) Therefore, my idiolect can legitimately swap between UK and US spellings in the course of a single sentence - you have been warned.

With that, let's proceed - I hope someone finds this useful.

Glossary A-Z